Interaction of beta-catenin and TIF2/GRIP1 in transcriptional activation by the androgen receptor

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Published on: October 27, 2020

Liang-Nian Song1, Edward P Gelmann

  • 1Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20007-2197, USA.

The Journal of Biological Chemistry
|September 6, 2005
PubMed

Insights

The oncoprotein beta-catenin interacts with the androgen receptor (AR) and coactivators like TIF2/GRIP1, forming a complex that enhances AR transcriptional activity. This interaction is crucial for regulating gene expression, with specific beta-catenin regions mediating these functions.

Area of Science:

  • Molecular Biology
  • Cellular Signaling
  • Cancer Research

Background:

  • Beta-catenin is a multifunctional oncoprotein involved in cell adhesion and signaling.
  • Androgen receptor (AR) is a nuclear receptor that regulates gene expression in response to androgens.
  • AR transcriptional activity is modulated by various coactivators and corepressors.

Purpose of the Study:

  • To investigate the interaction between beta-catenin and the androgen receptor (AR).
  • To elucidate the role of beta-catenin in AR transcriptional activity and ligand specificity.
  • To determine the mechanism by which beta-catenin influences AR-mediated transcription.

Main Methods:

  • Site-directed mutagenesis to identify key residues in beta-catenin for AR and TCF4 interaction.
  • Co-immunoprecipitation assays to confirm protein-protein interactions.
  • Reporter gene assays to measure AR transcriptional activity.

Main Results:

  • Beta-catenin directly interacts with the activation function-2 domain of AR, enhancing its transcriptional activity.
  • Beta-catenin binds to the P160 coactivator TIF2/GRIP1, facilitating a three-way interaction between AR, beta-catenin, and TIF2/GRIP1.
  • Specific beta-catenin residues mediate distinct interactions with AR and TCF4, allowing for selective functional modulation.
  • A C-terminal beta-catenin peptide inhibits AR-dependent transcription, suggesting a dominant-negative effect.

Conclusions:

  • Beta-catenin plays an integral role in the formation of the AR transcriptional complex.
  • The interaction between AR, beta-catenin, and TIF2/GRIP1 is critical for robust ligand-dependent transcription.
  • Targeting the AR-beta-catenin interaction may offer therapeutic strategies for AR-driven cancers.

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